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<head><title>Apache Tomcat/8.0.37 - Error report</title>
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<body><h1>HTTP Status 500 - Request processing failed; nested exception is java.lang.IllegalArgumentException: Attribute
    isn't nominal, string or date!</h1>
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<p><b>type</b> Exception report</p>
<p><b>message</b> <u>Request processing failed; nested exception is java.lang.IllegalArgumentException: Attribute isn't
    nominal, string or date!</u></p>
<p><b>description</b> <u>The server encountered an internal error that prevented it from fulfilling this request.</u>
</p>
<p><b>exception</b></p>
<pre>org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.IllegalArgumentException: Attribute isn't nominal, string or date!
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
	org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
	org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
</pre>
<p><b>root cause</b></p>
<pre>java.lang.IllegalArgumentException: Attribute isn't nominal, string or date!
	weka.core.AbstractInstance.stringValue(AbstractInstance.java:674)
	weka.core.AbstractInstance.stringValue(AbstractInstance.java:644)
	com.koala.learn.utils.WindowUtils.window(WindowUtils.java:129)
	com.koala.learn.utils.feature.WindowFeature.filter(WindowFeature.java:34)
	com.koala.learn.service.LabLearnService.addFeature(LabLearnService.java:129)
	com.koala.learn.controller.LabLearnBGController.addFeature(LabLearnBGController.java:74)
	sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	java.lang.reflect.Method.invoke(Method.java:498)
	org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221)
	org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
	org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:114)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
	org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
	org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
	org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963)
	org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
	org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
	org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
	org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
	org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
	org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
</pre>
<p><b>note</b> <u>The full stack trace of the root cause is available in the Apache Tomcat/8.0.37 logs.</u></p>
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<h3>Apache Tomcat/8.0.37</h3></body>
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